1. Field of the Invention
The present invention relates to a multi-screen display device formed by assembling screens of a plurality of image display devices using semiconductor light emitting devices as light sources to constitute a larger display screen, and particularly relates to an image display device capable of automatizing an operation to adjust luminance and chromaticity at a time of installing a multi-screen display device.
2. Description of the Background Art
There has hitherto been proposed a multi-screen display device, formed by assembling a plurality of projectors and used as a multi-vision, in which each projector detects present luminance of its own with a luminance sensor, a reference projector receives luminance information from the other projectors and then creates and transmits luminance correction data, and each projector makes correction based on the luminance correction data, thereby to make the luminance uniform among the projectors (c.f. Japanese Patent Application Laid-Open No. 10-90645 (1998), p. 2, FIG. 1).
There has also been a display device that computes a correction factor for generating target luminance/chromaticity to be set in each projector, and performs luminance/chromaticity correction on a video signal to be inputted, thereby to hold the target luminance/chromaticity of the projectors constant (c.f. Japanese Patent Application Laid-Open No. 2004-341282, paragraphs 0008 to 0043, FIG. 1).
There has further been proposed a display device that detects a peripheral temperature of an LED, compares the detected temperature with a peripheral temperature of the LED which was previously recorded at a time of initial setting, and controls a current to be supplied to the LED, thereby to hold luminous colors of the LED constant (c.f. Japanese Patent Application Laid-Open No. 2007-87816, paragraphs 0030 to 0061, FIG. 3).
In such conventional devices as described above, when projected light is to be detected, a luminance sensor needs to be arranged between a projection lens and a screen, which causes no problem at a time of adjustment, but makes it difficult to acquire luminance data since the luminance sensor blocks light during an actual operation period. It has thus been impossible to detect a temporal change in light source and thereby to make correction that automatically follows this temporal change.
Further, in the case of controlling a current to be supplied to the LED to adjust the luminance, there has been a problem of displacement of the chromaticity due to a change in each LED current. Moreover, unlike the case of a lamp light source, there has been a problem of displacement of the chromaticity due to individual changes in luminance of R, G and B of the LED, made by a temperature change and a temporal change.